The impact of academic research has long been measured using citation data, with the Journal Impact Factors playing a dominant role. However, scholarly citation, whilst important, is by no means a perfect or comprehensive reflection of impact. Citation data builds up over several years, so do not provide the necessary immediacy in fast moving fields, and a single Journal Impact Factors provides no information on the diverse levels of impact of different articles in the same journal. With discussion and debate about articles increasingly taking place on the web, there are now many additional sources of information which can be used to track and assess the impact of individual scientific publications.